AMD Athlon 64 X2 4400+ Dual-Core Processor - This desktop computer processor features dual cores, which is like having two processors in one. With two separate cores running at the maximum 2.2 GHz speed, you can multi-task supported programs with ease! It's also a 64-bit processor, so it will support future 64-bit programs and operating systems, giving you even more speed down the road. AMD's Enhanced Virus Protection - for users of Microsoft Windows XP with Service Pack 2 L1 Cache - 128KB + 128KB L2 Cache - 1MB x 2